Zao Onsen

Zao Onsen4.0

Zao Onsen is famous for its sulfuric springs that are among the most acidic in Japan. The acidic waters are considered effective with skin diseases and attract female travelers interested in skin care. Be warned that they are so acidic as to cause irritation in your eyes!

Among the most popular is a huge open-air pool called Dai Rotenburo that can apparently hold up to 200 people. It is very gorgeous and open from April to November.